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Windows 7: Very high DPC latency in Windows 7 x64 caused by storport.sys

29 Aug 2012   #1

Windows 7 Ultimate x64
Very high DPC latency in Windows 7 x64 caused by storport.sys

Hello all - hoping some real experts can shine a light on this one.

Installed a brand new mobo - Asus Sabertooth 990FX - and DPC latency checker was showing full red. Used Latency Mon to track down the culprit which was storport.sys. Searched everywhere for a driver update for storport in Win 7 and nothing exists.

Then went further and installed Windows Performance Toolkit and ran the Performance Analyzer to look at what was going on with storport. PA showed that the "RaidAdapterTimerDpcRoutine" was causing storport to spike so badly.

I'm not running any RAID drives - they're all set to AHCI in the BIOS, so I'm at a loss what to do next. All latest drivers & updates are installed. Are there RAID related drivers I can disable from device manager? Or switches in the registry?

Windows 7 x64 SP1
Asus Sabertooth 990FX mobo
AMD Phenom II X6 1090T black edition CPU
8gig ram


My System SpecsSystem Spec
03 Sep 2012   #2

Windows 7 Ultimate x64

Well I seem to have finally fixed my endless DPC problems. I performed a fresh install of Windows 7 and carefully installed all drivers and updates for everything in the following order:

- Asus motherboard drivers
- Flashed the BIOS and reinstalled latest vers.
- AMD CPU drivers
- All Windows 7 important updates incl SP1
- GPU drivers
- and lastly, the drivers for the external firewire audio device.

Hardware wise, I changed the slot that the GPU was installed on. I had it in PCI slot 3, and on reading the manual, they recommended slot 1 for the GPU. I also removed an Astrotek PCI firewire adapter card which was not being used. The new mobo has an external firewire slot that I've plugged into instead.

I also kept the driver installs "lean". Only installing the essentials. So I did not install the AI utilities for the Asus mobo, as I saw the AiCharger.sys misbehaving at one point. I also only installed the graphics drivers for the GPU - not PhysX, or 3D etc etc.

Something in that mix of changes was the secret sauce to fixing the DPC problems. Now I can run video, audio, flick between screens rapidly at any resolution and DPC never peaks above about 153. I've even still got aero running. I've got fingers and toes crossed that this remains stable, but this is the first time I've ever had Win 7 so calm since first installing it 18 months ago. I was never able to install and run my audio production software through Windows 7 due to these issues and had a dual boot machine so I could run XP side by side. Now I'm going to give it another go and see if I can run everything inside the one O/S.
My System SpecsSystem Spec
03 Sep 2012   #3

Windows 10 64 bit

I've been running Sonar 8.5 and now X1 64 bit on Windows 7 64 bit and no problems. I have also been running Pro Tools MP9, which is still 32 bit, on Win 7 64 bit without problems. I now have a new PC with an i7 3770 CPU which has the built in Intel HD4000 graphics, but my old system (Win 7 64 bit) used an ATI Radeon HD4850 graphic card and there were no problems or latency problems with that.

I did have some inital latency problems with the new system, which is using a Gigabyte Z77X UD5H motherboard and that turned out to be one of the utilites that Gigabyte included in the installation disc, along with the drivers. After removing the utilities DPC latency checker showed under 100 usec latency.

I have switched from a Firewire connected Focusrite Saffire Pro 40 to USB connected Roland Octa-Capture for my audio interface unit. I had some problems with Firewire, even with a T.I. Firewire chipset in the PC, and couldn't get the latency down much under about 11 ms as reported by Sonar. With the Octa Capture, Sonar reports 6.4 ms latency.
My System SpecsSystem Spec

03 Sep 2012   #4

Windows 7 Ultimate x64

Thanks Fireberd. When all this started, I initially went back to Focusrite for help, since the DPC issues were causing digital crackling and dropouts. They were the only manufacturer who genuinely tried to assist. In the end they told me I had an IRQ conflict with the GPU and apparently you can't change IRQ assignments under Win7. Anyway, I've been plagued with issues for months and months. Even under XP, I had to run the system with the GPU disabled (no drivers), which meant very low res screen and very slow refresh rate when scrolling up and down the screen. Microsoft, Asus, AMD were as useful as an ashtray on a motorbike.
My System SpecsSystem Spec
03 Sep 2012   #5

Windows 10 64 bit

Focusrite has very good tech support. I had a 30 day trial version of Pro Tools 10, which is not limited to only their equipment, and one of the things I was interested in was the Saffire pro 40's compatibility with Pro Tools 10, as it was supposed to be compatible. Focusrite tech support offered several suggestions on getting it working. Unfortunately they didn't help but ultimately Sweetwater Music's support gave me some info on getting it recognized, that finally worked. However, it was flakey with Pro Tools 10, sometimes it would immediately recognize it and other times I would have go through the procedure Sweetwater gave me which was basically a reinstall to get it to work. I had a hardware problem with the Saffire Pro 40 and the estimate to fix it (out of warranty) was almost what I paid for it so I dumped it for a USB connected device and after trying a couple I settled on the Roland Octa-Capture. Although it was primarily for Sonar, I tried it with Pro Tools 10 and it was immediately recognized and installed by Pro Tools, and I didnt have to "jump through hoops" like I did with the Saffire Pro 40 to get it working with Pro Tools.
My System SpecsSystem Spec

 Very high DPC latency in Windows 7 x64 caused by storport.sys

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